The present invention relates to a method and apparatus for purifying a raw material gas for use in an industry and also to a purifier used in said purifying method and a method of manufacturing said purifier. More and more particularly, the invention relates to a method for removing oxygen and a water component contained in an inert gas, a highly purified gas such as H.sub.2, NH.sub.3 and CO.sub.2 for use in the industry and a raw material gas for use in manufacturing a semiconductor device by means of said purifier.
Generally, in order to eliminate a small amount of oxygen contained in the raw material gas, use is made of a metal-carrier catalyst such as a nickel metal (Ni)-alumina carrier (Al.sub.2 O.sub.3) catalyst. The catalyst mentioned above is effective as long as the raw material gas to be purified does not decrease the activity of the catalyst or the extent of deoxygenation from a hydrogen gas or an inert gas such as N.sub.2, Ar or He gas. However, the catalyst is not so effective for the deoxygenation from a gas such as NH.sub.3, CO, because the catalyst becomes inactive due to the above mentioned gas which functions to make it inactive. Moreover, since the catalyst must be heated to a very high temperature (i.e., over 300.degree. C.) in the presence of a hydrogen gas, in order to activate or reactivate the catalyst, the handling and treatment of the catalyst becomes difficult. Further, since the catalyst mentioned above does not show the activity for the water component, in order to remove the water component it is necessary to arrange a separate water component absorption tank in which various zeolites are contained.
The inventor has proposed in U.S. patent application No. 622,757 filed on June 20, 1984, now U.S. Pat. No. 4,565,677, a method of purifying the raw material gas by using a purifier comprising a carrier and a hydrogenated amorphous substance of Si, Ge, P or As. In this method, the purifier functions to selectively absorb the oxygen from the raw material gas. Such characteristics occur due to the fact that an atom in the hydrogenated amorphous substance has a dangling bond with which an oxygen atom is coupled. In this method, in order to absorb the water component in the raw material gas, there is provided a separate tank containing zeolites.
The inventor has conducted various experiments and analyses and has recognized the fact that the hydrogenated amorphous substance can absorb a water component (H.sub.2 O) in addition to the oxygen component (O.sub.2) in the same mechanism, so that it is possible to remove simultaneously a small amount of water component together with the oxygen component from the raw material gas for industrial use. It has been further confirmed experimentally that since a reaction between the dangling bond of the atom of the hydrogenated amorphous substance and oxygen atom in the raw material gas proceeds in a chemical manner, the hydrogen absorption efficiency becomes higher as the temperature increase, whilst the water component absorption efficiency of the zeolite becomes lower when the temperature is increased. Therefore, it is rather difficult to remove both the oxygen component and the water component.